1. Field of the Invention
The present invention relates to a wrench, and more particularly to a wrench having an adjustable mechanism for engaging with and for driving the fasteners of different sizes.
2. Description of the Prior Art
U.S. Pat. No. 4,440,047 to Robbins discloses a typical wrench having a number of longitudinal or inclined grooves formed in the driving head thereof for slidably receiving a number of drive inserts respectively. A number of springs are required to be engaged into the grooves and engaged with the drive inserts for biasing the drive inserts to engage with the fasteners to be driven. The drive inserts each is required to be engaged with and biased by a spring member such that a complicated structure is thus formed and may not be easily assembled.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional wrenches.